Tire molding machine

ABSTRACT

A tire molding machine comprising a core or center mechanism adapted to be expanded radially and converted from a generally cylindrical to a toroidal or tire shape, side wall mold sections and a tread mold section movable into position vis-a-vis such core when in tire shape to form a tire mold cavity, injection means to fill such cavity with an elastomer to be heat cured to form a tire, such core being then collapsed to cylindrical shape and radially contracted while the side wall and tread mold sections are withdrawn to permit removal of the tire.

Waited States Patent Turk [451 Feb. 25, 1975 1 TIRE MOLDING MACHINE [75]Inventor: Leonard G. Turk, Akron, Ohio [73] Assignee: NRM Corporation,Akron, Ohio [22] Filed: Dec. 26, 1973 [21] Appl. No.: 428,140

Related U.S. Application Data [62] Division of Ser. No. 143,847, May 17,1971, Pat. No.

[52] US. Cl 425/242, 156/125, 156/417, 156/420, 156/394, 156/110,425/46, 425/129, 425/40 [51] Int. Cl B29h 3/08, B29h 5/02, B29h 17/00,B29f l/OO [58] Field of Search 425/39, 35, 45, 46, 52, 425/54, 242;18/42 T [56] References Cited UNITED STATES PATENTS 2,476,884 7/1949Maynard 18/42 T UX 2,763,317 9/1956 Ostling et al 425/52 X 3,337,9188/1967 Pacciarini et a1. i 425/39 3,396,221 8/1968 Balle et al 425/43 X3,457,594 7/1969 Baudon 425/35 3,459,849 8/1969 De Ronde 425/45 X3,464,090 9/1969 Cantarutti 425/46 3,645,655 2/1972 Beneze 425/353,703,346 11/1972 Deboeur 425/46 FOREIGN PATENTS OR APPLICATIONS1,928,829 12/1970 Germany 425/46 Primary Examiner-J. Howard Flint, Jr.Attorney, Agent, or FirmDonnelly, Maky, Renner & Otto [57] ABSTRACT 5Claims, 6 Drawing Figures PATENTEU SHEET 1 OF 5 vm mm On PATENTEU3,868,203

' sum s 115 5 TIRE MOLDING MACHINE This is a division of applicationSer. No. 143,847, filed May 17, 1971 now US. Pat. No. 3,782,871.

This invention relates generally as indicated to a tire molding machineand more particularly to a machine for the production of tires having aunique core or center mechanism.

Tires are conventionally made by the construction of a rather elaboratetire carcass usually made on a drum, such carcass being comprised of aplurality of elements such as beads, tire ply materials wrapped aroundsuch beads, and tread stock and tire side wall materials appliedthereto. The carcass is then positioned in a tire press which throughpressure shapes the carcass to tire shape and then heat cures theelasotmeric materials to form a tire. The practical possibility ofinjection or other type molding of tires has been extremely illusiveprincipally because of the inability to provide a machine which wouldhave a suitable tire shape core to form the tire cavity which could thenreadily be collapsed for removal of the cured tire from the machine.Most such prior machines have included cores which could not be readilyradially expanded nor readily converted to a toroidal or tire shape andthen collapsed or contracted to permit removal of the tire from themachine.

With the present invention there is provided a machine utilizing a corewhich can radially be expanded and then quickly converted to a toroidalor tire shape. There can be applied to the core tire beads or other tirematerials such as belts and the like. Tire side wall mold sections andtread mold sections can then be quickly and properly positionedvis-a-vis the expanded core to form a tire cavity. Elastomeric materialmay then be injected into the cavity or the cavity can be formed abouttire materials positioned on the core for the compression orinjection'molding of the tire in the machine. After the elastomericmaterials are heat cured, the side wall mold sections and the tread moldsection may be removed and the core collapsed so that the formed tiremay readily be removed from the machine.

It is accordingly a principal object of the present invention to providea tire molding machine utilizing a cylindrical core which can beexpanded radially and then converted to toroidal or tire shape to formthe interior surface of a tire mold cavity.

Another principal object is the provision of a tire molding machineutilizing a generally cylindrical core which can be converted to atoroidal or tire shape to cooperate with side wall and tread moldsections to form a tire cavity.

Yet another principal object is the provision of a tire making machinefor the injection or compression molding of tires utilizing ahorizontally disposed core having a substantially rigid surface whichcan be expanded radially and then converted to generally toroidal ortire shape to form with side wall and tread mold sections a tire cavity.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention,then, comprises the features hereinafter fully described, the followingdescription and the annexed drawings setting forth in detail a certainillustrative embodiment of the invention, this being indicative,however, of but one of the various ways in which the principles of theinvention may be employed.

In said annexed drawings: FIG. 1 is a side elevation of a machine inaccordance .with the present invention, such machine being partiallybroken away and in section and in open or tire removal condition;

FIG. 2 is a fragmentary side elevation similar to FIG. 1 showing themachine partially closed and the core radially expanded with the beadsof the tire to be formed in position;

FIG. 3A is an enlarged fragmentary vertical section of the machine inthe condition of FIG. 2;

FIG. 3B is a broken continuation of FIG. 3A;

FIG. 4 is an enlarged fragmentary quarter section of the machineillustrating the tire cavity thus formed; and

FIG. 5 is a quarter section similar to FIG. 4 illustrating the cavitypartially opened with the tread mold section radially expanded.

THE MACHINE GENERAL ARRANGEMENT Referring first to FIGS. 1 and 2, itwill be seen that the machine is mounted on an elongated base 10, at oneend of which is a core drive housing 11. The core 12 driven andcontrolled from such housing projects in cantilever fashion therefromthrough axially movable head stock assembly 13. The head stock assemblyis mounted for limited axial movement on laterally spaced rails 14mounted in the base 10. Rollers indicated generally at 15 support suchhead stock assembly for movement axially along the base.

At the opposite end of the core 12 there is provided a two part tailstock assembly 17 which includes an outer carriage 18 and an innercarriage 19, both mounted on the base for movement axially of the corein the same manner as the head stock assembly 13. The outer carriage 18of the tail stock assembly 17 as well as the head stock assembly 13maybe locked to the base by the use of conventional shot pin assembliesseen more clearly at 20 and 21.

The head stock assembly 13 includes a main annular bolster plate 23having an outwardly projecting hub 24 surrounding the control shaftassembly 25 of the core 12 which projects from the core drive housing11. A plurality of radially extending gusset plates 26 extend from thehub to the bolster plate 23. An annular plate of insulating materialindicated generally at 27 is secured to the interior of the bolster 23and an annular housing 28 projects axially inwardly therefrom.

The interior of the housing 28 is provided with a plu-' rality ofaxially inclined T-slots 29, each pair of which has a sliding fit withTs 30 on the exterior of slide blocks or segments 31. There may beapproximately eight to a dozen or more such segments mounted in suchmanner on the interior of the axially projecting housing 28. A stop pin32 riding in slot 33 limits outward movement of the sectors with respectto the housing 28. On the inside of each block 31 is a tread mold sector34, such sectors forming the annular tread mold section when the blocks31 are radially closed.

The head stock assembly 13 also carries annular platen 36 on which ismounted side wall mold section 37 which includes at its radially innerend a bead or toe ring 38. The platen 36 is mounted on the distal endsof rods 39 of piston-cylinder assemblies 40, the cylinders of which aremounted on the exterior of bolster 23. The platen 36 is thus movablewith respect to the bolster and normally sufficient pressure will beapplied to the blind end of such piston-cylinder assemblies 40 to urgethe platen 36 away from the bolster and the tread plate 53 on the frontof the bolster plate 50 supports platen 54 to which is secured side wallmold section 55, the inner edge of which includes bead or toe ring 56.The platen 54 includes annular slide plate 57 which butts against theaxially projecting ends of the tread mold sector blocks 31.

In FIG. 1 the machine is shown fully opened so that a finished tire T,shown in phantom lines, may be removed from the machine by simplyremoving the tire from the end of the projecting core 12. In such openposition as seen in FIG. 1, after the tire T has been removed, theoperator may then place bead rings on the toe rings 56 and 38 if suchbead rings are desired in the final tire product. Such bead rings areillustrated at 60 in FIG. 2. With the bead rings in position. themachine may now begin its closing operation which will result in theformation of a substantially perfect tire shape cavity.

The first step in closure is to index the tail stock 17 toward thecantilevered projecting end of the core 12 to close up the space betweenthe inner carriage 19 and the core through which the finished tire isremoved. This indexing of the tail stock may be accomplished by arelatively long stroke and small diameter pistoncylinder assembly 61.The initial purpose in indexing the tail stock is to connect such tailstock to the projecting end of the core as seen more clearly in FIG. 3A.

THE CORE Referring now more particularly to FIGS. 3A and 38, it will beseen that the core 12 is mounted on a main tubular shaft 65 which ispart of the cantilever shaft assembly 25. The shaft 65 is connectedthrough flange 66 to hub 67 of tubular shaft 68 journalled as at 69 inthe frame of the core drive housing 11. Rotation of the connectedtubular shafts 68 and 65 will cause the entire core to rotate, ifdesired, for a purpose hereinafter described.

In addition to being rotatable, the core is also capable of radialexpansion and contraction as well as conversion to toroidal or tireshape after expansion. A comparison of FIGS. 1 and 2 illustrates thecore contracted and radially expanded, respectively. In FIG. 2 the corehas, however, not yet been converted to tire or toroidal shape. Radialexpansion and contraction of the core is, of course, principallynecessary to permit the finished tire T to be removed from the machine.Such expansion characteristic also permits tire materials such as theaforenoted bead rings 60 to be properly positioned in place prior toformation of the tire cavity.

Radial expansion of the core is accomplished by annular racks 72 mountedin each end or shoulder of the core. Such racks are capable of movementbetween the axially spaced radially extending shoulder walls 73 and 74.In each core and housing as provided by such walls there is mounted aplurality of pinions 75 which, in addition to being in mesh with theannular rack surface of rack 72, are also in mesh'with radiallyextending racks 76 supporting a plurality of core end segments 77.Accordingly, as each annular rack 72 moves axially inwardly, the pinionsare caused to rotate and radially shift the racks 76 and accordingly thecore end segments 77 move radially outwardly. When the annular racks 72move axially outwardly, the core ends are accordingly radiallyretracted. Suitable adjustable stops or limits may be provided preciselyto control the position of the core ends both contracted and radiallyexpanded.

Movement of the annular racks is obtained by three shoulder controlscrews 80, only two of which are shown in the somewhat distortedsectional views of FIGS. 3A and 3B.

Reverting momentarily to FIGS. 1 and 2, it will be seen that on top ofthe core drive housing 11 there is provided a drive unit 81 which mayinclude a variety of rotational position sensors. Such drive unit 81drives timing belt 82 which drives timing belt sheave 83 secured to hub84 journalled on shaft 68. The shoulder drive is thus independent of theshaft 68. The hub 84 includes a radial flange 85 to which is securedinternal ring gear 86. Such internal ring gear is in mesh with threepinions 87, spline connected to the respective shoulder control screws80. Nuts 90, held against rotation and in mesh with the control screws80, are interposed between such control screws and each annular rack 72.It will be appreciated that the control screws 80 have sections ofopposite hand threads at each end as seen by comparing FIGS. 3A and 33to obtain the desired expansion and movement of the drum ends, thelatter hereinafter described.

Normally when the control screws are rotated, the entire drum ends wouldtend to move toward or away from each other. To resist this movementtendency and thus provide the required reaction to obtain the radialexpansion of the drum ends, there is provided shoulder hold pneumaticcylinders 92 and 93 as seen in FIGS. 3A and 38, respectively. Suchshoulder hold cylinders will maintain the drum ends in place duringinitial rotation of the control screws 80 to obtain the desired drum endexpansion. When the annular racks have reached their limit of movement,continued rotation of the control screws 80 will overcome the resistanceor drag of the shoulder hold cylinders then permitting the shoulders ofthe core to move toward each other as the crown of the core is expandedto convert the core from the cylindrical shape shown to a toroidal ortire shape to form the interior of the tire cavity. I

The shoulder hold piston-cylinder assembly 92 has its rod 94 anchored at95 to the hub 51 of the inner carriage 19. Any other suitable anchor forthe rod would,

however, suffice.

The cylinder portion of the assembly 92 is mounted on a sliding sleeve96. Suitable bushings 97 are provided to permit the sleeve to slidealong tube 98 which projects horizontally on the tail stock and isaligned with the axis of the core 12. The tube 98-is provided with anelongated axial slot 100 through which extends key 101 connecting theouter sleeve 96 and thus the cylinder of the assembly 92 to a thrustbushing 102 in which is journalled the end of tubular shaft 103.Accordingly, axial movement of the cylinder of the assembly 92 willcause axial movement or exert a pressure of axial movement on thetubular member 103.

A latch rod 105 extends through the tubular member 103 and is actuatedby piston-cylinder assembly 106 mounted on the ends of support rods 107which are anchored in the thrust bushing 102. Actually such latch rodmay be of a two part construction, such two parts being interconnectedby a thrust bearing 108. The purpose of the latch rod is to connect anddisconnect the tail stock from the projecting end of the core 12 andalso to connect and disconnect the tubular shaft 103 to the end orshoulder 110 of the core 12 to permit the shoulder hold cylinderassembly 92 to function. Such connection is accomplished through thelatch mechanism shown generally at 112.

Such latch mechanism includes a socket member 113 secured in the tubularshaft 65 of the core. Such socket member includes inwardly directedlatch recesses 114 which cooperate with pivoted latch members 115 and116. Such latch members are coaxially pivotally mounted at 117 to theend of the tubular shaft 103 and are urged by compression spring 118 toa retracted or recess clearing position. When the piston-cylinderassembly 106 is extended, extending latch rod 105, the latch members 115and 116 are pivoted outwardly about the pivot 117 engaging the recesses114. The socket member 113 is provided with a radially extending key 120which is secured between the radially extending walls 73 and 74 of thecore end. Accordingly, when the tail stock is indexed into position, thetubular shaft 103 telescopes within bronze bushing 121 so that when thepiston-cylinder assembly 106 is extended, the cylinder of the assembly92 will be locked to the drum end holding such shoulder or end inposition as the control screws 80 expand the core end through theannular rack, pinions and radially movable segments.

The shoulder hold cylinder assembly 93 is connected to the opposite coreend in a slightly different fashion. Referring now to FIG. 313, it willbe seen that the rod 125 of the assembly 93 is anchored at 126 to theframe 127 of the core drive housing 11. The cylinder of the assembly 93is mounted on sleeve 128 provided with bushings 129 at opposite ends sothat such sleeve is slidably mounted on the tubular shaft 68. A bracket130 extends from the sleeve locking the sleeve to tubular rod 131. Suchrod is connected to annular frame 132 which is in turn connected torotatable annular member 133 through the radially extending rollerconnection shown at 134. Rods 135 connected to the annular member 133 bythe fasteners 136 then are connected directly to the end wall structure74 of the core end or shoulder.

The core 12 is constructed in such a manner as to be converted in aprecisely controlled fashion from the cylindrical shape to a toroidal ortire shape. The surface of the core may include a relatively stiff yetelastic material 140. The beaded annular ends of the elastic material140 extend over the shoulder provided by the shoulder segments 77 andare secured between such segments and pilot ring segments 141. Suchpilot ring segments have an exterior surface shaped to provide a pilotguide for the toe rings as they move axially toward the end of theradially expanded core. Beneath the elastic outer covering of the corethere is provided a multiplicity of metallic elements which provide afirm undersurface for the core both in its cylindrical and its expandedor toroidal shape. Pivoted to each of the shoulder segments is ametallic hinge member 144, each such hinge member being provided with aslot to receive in a slidable fit axially extending flexible metallicstrip 145. Each metallic strip is secured to one side of a respectivecrown element 146. Reading from left to right in FIGS. 3A and 3B therewill be a shoulder element, hinge element hingedly connected to theshoulder element, flexible metallic strip slidably connected to thehinge element and secured to the crown segment 146, another strip 145and hinge element, interconnected in the same manner with the latterhingedly connected to the opposite shoulder segment. The illustratedmetallic elements form circumferentially of the core a metalliccontinuum when the core is in its smallest condition as seen in FIG. 1.

The crown segments 146 are supported for movement radially of the coreby the double scissors or X linkage seen perhaps more clearly in FIGS. 4and 5. Each linkage system includes an inner pair of crossed links 148and 149 pivotally connected to each other at 150. The inner or proximalend of each link is pivoted at 151 and 152 to circular frames 153 and154, respectively. Such circular frames are mounted on center controlscrew 155 which has opposite hand thread portions 156 and 157 in meshwith nuts 158 and 159 positioned in the frames 153 and 154,respectively. Such circular frames are provided with apertures throughwhich the control screws 80 freely fit without interference. Pivoted tothe outer ends of the inner pair of links 148 and 149 are a second pairof links 162 and 163. Such links are pivotally connected to each otherat 164. The outer ends of the outer pair of links are provided withrollers indicated at 165 and 166 which are mounted in axially extendingslots 167 and 168 in the crown segment 146. Such crown segment is alsoprovided with a radially extending slot 170.

The radially extending slot accommodates guide rollers extending axiallyof the pivots 164 and 150 which interconnect the two pair of crossedlinks. In the collapsed or cylindrical condition of the core both suchrollers will be within the slot while in the extended or tire conditionof the core only the roller projecting from the pivot 164 will be withinthe slot. The slot con struction in the crown segments maintains thecrown segments properly oriented with respect to the rest of the core.The crown segments are in the shape of a tire crown and as the coreexpands by rotation of the central control screw 155, the flexiblemetallic strips 145 extending between the hinge elements 144 and thecrown segments will wrap around the exterior surface of the crownsegments. It is also noted that in tire shape, the strips havetelescoped into the hinge. elements. This is accomplished as thedistance between the end of the hinge elements and the crown edgeshortens.

As seen in FIG. 3B, the central control screw 155 for the drive of thecrown segments is journalled within the shaft elements 65 and 68. Suchscrew shaft is driven through sprocket 170 secured to the outer endthereof as seen in FIG. 3B. A drag brake 171 associated with thesprocket prevents overtravel of the shaft. The sprocket 170 is drivenfrom a core crown drive motor 172 on the top of the core drive housing11 as seen in FIG. 1. Again such drive for the core crown may includerotational position sensors so that the crown may be expanded radiallyin synchronism with the axial inward movement of the core shoulders orends. If it is desired to rotate the core this may be accomplishedthrough core rotation drive motor 173 as seen in FIG.

7, 1, such drive motor driving belt 174 trained about belt sheave 175keyed to the tubular shaft 68. An inner brake or clutch indicated at 176in FIG. 38 may be employed in connection with the rotational drive 173precisely to control the rotation of the core. Rotation of the core maybe desirable prior to the closing of the side wall and tread moldsections about the core for the application of special tire elementssuch as tread stock, reinforcing belts, or reinforcing fabric.

The closing of the side wall mold sections about the core as it expandsor following its expansion is accomplished by a pair of relatively largeclamp pistoncylinder assemblies as indicated at 180 and 181 in FIG. 1,one of each pair being on laterally opposite sides of the machine. Therods of such clamp cylinders may be connected at 182 and 183 to the hubsof the frames supporting the tail stock inner carriage 19 and the headstock bolster 23. The cylinders of such assemblies may be mounted on thetail stock outer carriage and the frame of the core drive housing,respectively. When the tail stock is in its inner position, the tailstock outer carriage will be locked to the rails 14 and extension of theclamp cylinders 180 will move the tail stock inner carriage with respectto the tail stock outer carriage. Similarly, the clamp cylinders 181will cause the head stock 13 to move axially toward the tail stock andwith respect to the fixed core drive housing 11.

When the tire cavity is formed by conversion of the core to toroidalshape and the movement of the side wall mold sections toward each other,the final movement of the mold section 37 or the head stock 13 radiallyclosing the tread mold section 34, a pair of injection molding machinesshown generally at 190, one on each side of the tail stock, are indexedinto position for injection through retraction of index cylinderassemblies 191.

Such injection molding machines may be of a generally conventionalvariety and include hoppers 192 for the feed of raw material. Preferablysuch injection molding machines are of the reciprocating screw typewherein a screw in heated barrel 193 is rotated to plasticize the rawmaterial, such rotation being obtained by drive motor 194. As the screwrotates, it prepares a shot of plasticized material in front of it andthe screw backs off retracting hydraulic cylinder 195. When the shot isprepared for injection, the piston of the assembly 195 indexes forwardforcing the plasticized material through lance or nozzle 196 into themold cavity. As seen perhaps more clearly in FIG. 4, the tip of thelance or nozzle will be positioned adjacent the cavity by the indexcylinder assembly 191. Such injection molding machines are mounted forsliding movement on the outer tail stock carriage and may be locked ininjection position when properly indexed. To accommodate the lance ornozzle for sliding indexing movement, there is provided a relativelylarge sleeve bushing indicated at 197 in the inner tail stock carriage.

OPERATION Referring initially to FIG. 1, the machine is shown in itsopen condition and the previously produced tire T may be removed betweenthe projecting end of the core 12 and the inner carriage 19 of the tailstock 17. In such position the tail stock is shown in its fullyretracted position. Also in such position the head stock 13 has beenretracted by the clamp piston-cylinder as semblies 181 automaticallyradially opening the tread mold sectors 34. The operator may now placebead rings on the toe rings 56 and 38.

Referring 'now to FIG. 2, the first step in the closing of the machineis accomplished by the radial shoulder expansion of the core 12. Thisis, of course, done after the tail stock has moved into position againstthe projecting end of the core and the shoulder hold pistoncylinderassembly 92 is connected to the end of the core through the latchmechanism 112 held in its locking condition by the piston-cylinderassembly 106. With the shoulder hold cylinder assemblies 92 and 93exerting a predetermined axially outward force on the ends of the core,the shoulder drive 81 is utilized to rotate the three control screwswhich through the nuts in mesh with the opposite hand threads on suchscrews move the annular racks 72 axially inwardly to move the shouldersegments 76 radially outwardly through the plurality of pinions 75. Thispositions the shoulder of the core opposite the toe rings 56 and 38 ofthe side wall mold sections to be engaged thereby as seen in FIGS. 3Aand 3B.

When the core is thus expanded, the side wall mold sections may bebrought into position bearing thereagainst by initial operation of theclamp piston-cylinder assemblies 180 and 181. Now with the tail stocklocked in position through a shot pin assembly 20, the core is convertedto toroidal shape by operation of both the control screws 80 and thecenter control screw through the respective drives 81 and 172. Thecontrol screws 80 overcome the force exerted by the shoulder holdcylinders 92.and 93 causing the entire core ends to move toward eachother as the crown segments 146 are radially expanded by operation ofthe crown control screw 155.

As such shoulders or ends of the core move toward each other, thepiston-cylinder assemblies 92 and 93 will retract with the cylindersmoving axially along the extending rods thereof. As the shoulders of thecore move toward each other and the crown moves radially outwardly, theside wall mold sections follow through extension of the clamppiston-cylinder assemblies and 181.

As illustrated perhaps more clearly in FIGS. 4 and 5 when the side wallmold sections 55 and 37 have achieved their final position vis-a-vis thecore with the latter converted to toroidal shape, the tread moldsections 34 are still not yet in position to complete the tire cavity.

The axially projecting end faces of the blocks 31 will initially abutagainst annular slide plate 57 precluding further axial movement of thetread mold sectors 34. At the time of such abutment, the side wall moldsections 55 and 37 are in their final position. The piston rods 39 ofthe piston-cylinder assemblies 40 are secured at 201 to platen 36 onwhich the side wall mold section 37 is mounted. Such rods 39 extendthrough bushings 202 in bolster 23. There is accordingly permittedrelative movement between the platen 36 or the side wall mold section 37and the bolster 23 which is moved by the relatively large clamppiston-cylinder assemblies 181.

As previously indicated, air pressure is normally provided on the blindend of the cylinder assemblies 40 to urge the bolster 23 and the platen36 apart to the maximum extended position. In such position the blocks31 will be at their radially extended position as seen in FIG. 5.Further extension of the clamp piston-cylinder assemblies 181 will nowmove the bolster 23 toward the platen 36 or the side wall mold section37 compressing the air in the cylinder assemblies 40. This causes thannular housing to move axially to the left as seen in FIG. forcing theblocks 31 radially inwardly due to the inclined T and slot connection30-29. Continued movement of the bolster by extension of the clamppistoncylinder assemblies 181 will cause the parts to achieve theposition in FIG. 4 with the tire cavity now formed and closed.

With the cavity now completed and with any beads, belts or reinforcingstructures in place, the injection molding machines 190 are now indexedinto position to move the lances 196 thereof through the bushings 197and into position with the tip or nozzle adjacent the cavity. When insuch injection position, the injection molding machine may be locked inplace to prevent the injection pressure from overcoming the pressure ofthe cylinder assembly 191 and to prevent the retraction of the machine.

As is the case in conventional injection molding machines, the shothaving previously been prepared by the rotation of the screw, all thatneed be done is to index the cylinder assembly 195 to inject plasticmaterial into the cavity. As soon as the injection cycle is completed,the injection molding machine is unlocked and the piston-cylinderassembly 191 is extended to retract the lance to the position seen inFIG. 5. Heat may now be applied to the cavity through the circulation ofsteam or other heating medium through the platens which may be providedwith chambers indicated at 205, 206 and 207 for such purpose. It will,of course, be appreciated that heat may be applied to the cavity byother means such as electrical resistance elements or a high frequencyfield.

After a predetermined cure cycle, the machine will now open. This isfirst accomplished by retraction of the bolster 23 by retraction of theclamp pistoncylinder assemblies 181. This moves the parts from therelative position shown in FIG. 4 in the closed condition of the cavityto the partially opened conditioshown in FIG. 5. As the bolsterinitially withdraws, the force exerted by the piston-cylinder assemblies40 causes the blocks 31 to move radially outwardly and the tread moldsectors 34 are thus withdrawn radially from the cavity. This permitsproper stripping of the tread mold sectors from the tread portion of theformed tire.

Continued retraction of the piston-cylinder assemblies 180 and 181 willwithdraw the side wall mold sections from the sides of the cavitypermitting the core 12 now to commence conversion to a cylindricalshape. This is accomplished by rotation of the control screws 80 movingthe core ends radially outwardly and also by rotation of the centercontrol screw 155 moving the crown segments 146 radially inwardly. Oncereturned to the cylindrical condition as seen in FIG. 2, the core endsare radially contracted by moving the annular racks axially outwardly.This reduces the diameter of the core to less than the ID. of the beadsof the tire. The tail stock is now unlatched and withdrawn to permit thetire to be extracted axially of the core and through the opening betweenthe projecting end of the core and the inner carriage of the tail stockas seen in FIG. 1.

It can now be seen that there is provided a machine utilizing a uniquecore or center mechanism enabling the quick formation of a tire cavityas well as the quick stepwise disassembly of the cavity and collapse ofthe core to permit the finished tire to be removed from the machine.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A tire making machine comprising a cylindrical core, side wall moldsections movable axially of said core, said core projecting axially incantilever fashion from one of said side wall mold sections and beingseparable from the other of said side wall mold sections to permit theplacement of tire components over said core, each side wall mold sectionincluding toe rings projecting axially inwardly thereof adapted tosupport tire components such as bead rings, means operative to expandsaid core radially from a diameter less than that of said toe rings to adiameter greater than that of said toe rings while maintaining itscylindrical shape to form a shoulder on the ends of said drum adapted tocooperate with said toe rings to retain such bead rings thereon, meansoperative to convert said core from such cylindrical shape to tire shapeto form the interior of a tire cavity when said side wall mold sectionshave moved axially thereagainst, an elastic yet substantially rigidsurface on said core in both the cylindrical and tire shape thereof,-andinjection means operative to fill the cavity remaining after placementof such components with an elastomeric material.

2. A machine as set forth in claim 1 including a radially movable treadmold section mounted on one side wall mold section, and means operativeradially to move said tread mold section when said side wall moldsections are in position to complete such tire cavity.

3. A machine as set forth in claim 2 including axially inclined guidemeans interconnecting said tread mold section and the side wall moldsection on which it is mounted operative to cause such radial movementof said tread mold section.

4. A machine as set forth in claim 1 including clamp cylinders operativeto hold said side wall mold sections in proper position vis-a-vis saidcore when the latter is in tire shape.

5. A machine as set forth in claim 1 including means to apply heat tosuch cavity to cure a tire therein.

1. A tire making machine comprising a cylindrical core, side wall moldsections movable axially of said core, said core projecting axially incantilever fashion from one of said side wall mold sections and beingseparable from the other of said side wall mold sections to permit theplacement of tire components over said core, each side wall mold sectionincluding toe rings projecting axially inwardly thereof adapted tosupport tire components such as bead rings, means operative to expandsaid core radially from a diameter less than that of said toe rings to adiameter greater than that of said toe rings while maintaining itscylindrical shape to form a shoulder on the ends of said drum adapted tocooperate with said toe rings to retain such bead rings thereon, meansoperative to convert said core from such cylindrical shape to tire shapeto form the interior of a tire cavity when said side wall mold sectionshave moved axially thereagainst, an elastic yet substantially rigidsurface on said core in both the cylindrical and tire shape thereof, andinjection means operative to fill the cavity remaining after placementof such components with an elastomeric material.
 2. A machine as setforth in claim 1 including a radially movable tread mold section mountedon one side wall mold section, and means operative radially to move saidtread mold section when said side wall mold sections are in position tocomplete such tire cavity.
 3. A machine as set forth in claim 2including axially inclined guide means interconnecting said tread moldsection and the side wall mold section on which it is mounted operativeto cause such radial movement of said tread mold section.
 4. A machineas set forth in claim 1 including clamp cylinders operative to hold saidside wall mold sections in proper position vis-a-vis said core when thelatter is in tire shape.
 5. A machine as set forth in claim 1 includingmeans to apply heat to such cavity to cure a tire therein.